We had an interesting one with an iR1730i where the client needed to use manual fax. A colleague of mine jumped through hoops of fire to figure this out.
If you need manual fax on the iR1700 or iR2500 range you can enable it in service mode by going to #special >sswitch ssw27, set bit 7 (the one on the extreme left) to 1 and then restart the machine. Also if you need to set the incoming rings on the iR1700 you get there by pressing the volume button on the side of the control panel. I'm sure some of you know this already, but I have found this to be very useful information.